Recirculated Aquaculture Systems Advantages & Disadvantages Good Practice Workshop, 2014, Copenhagen, Denmark Jesper Heldbo, Ph.D., M.Sc., Secretary General AquaCircle 1
RAS Advantages 1 Low water requirement - can utilise small water sources and/or be connected to the public water supply Type of farm Liter new water per kg fish production Traditional pond farming 40-50.000 Reuse moderate 25.000 Reuse intensive 10.000 Partly Re-circulation 5.000 Moderate Re-circulation 500 Intensive Re-circulation 50-400 1 kg beef 15.500 1 liter of milk 150 1 kg of pork 4.800 1 kg of chicken 3.900 1 kg of rice 3.400 1 kg potatoes 900
RAS Advantages 2 The system can achieve optimal temperature and enables optimal and stable production all year round, independent of seasonal variation, this makes the production predictable for 365 days Growth performance atlantic salmon %/day 1,80 1,60 1,40 1,20 1,00 0,80 500 g 1 kg 2 kg 3 kg 4 kg 5 kg 0,60 0,40 0,20 0,00 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 Sea temperature celcius
RAS Advantages 3 The required area for a given production is relative small, because a very high density and a high growth rate is possible in the controlled environment Fish size (gram per fish) Density/Biomass (kg per m 3 water) Numbers (pcs. per m 3 ) 2 22 11.000 10 35 2.833 50 60 1.200 100 50 500 2.000 75 38 5.000 85 17
RAS Advantages 4 Reduced risk of diseases - All incoming water can be filtrated and afterwards UV-disinfected - All entrance to the fish farm is through a disinfection room The incoming water can be further treated to achieve the desired quality - If the water is not suitable for fish farming undesirable substances like iron, manganese, aluminium etc. can be feasible removed - because very little water is used Control and traceability - PC Monitoring and Surveillance Optimal and stable production conditions - Securing high and stable quality of the fish
RAS Advantages 5 8. Due to low water consumption in RAS also the discharged water volume is minimal and can be controlled and treated. 9. Sludge from the system can be concentrated to desired dry matter content and appear as an odour free fertiliser or can be used in biogas-production. The fish farm can be established near cities and thereby close to market This means less transportation costs and less CO 2 footprint The transportation costs for 1 kg fresh salmon from Norway to USA by airfreight is approx. 1½ US$, to China app. 2 US$
RAS Disadvantages 1 Advanced system Security system in function at any time Regular power supply with back-up necessary RAS requires skilled staff for management This require full focus on the daily routines.
RAS Disadvantages 2 The RAS is relative expensive to establish and has a relative high energy consumption. Therefore the RAS requires a minimum production capacity for an economical operation. Type of farm Liter new water per kg fish production kwh pr kg fish produced per year (new-old) Water treatment Total investment per 1 kg production capacity Traditional 50.000 0 None? Reuse moderate 25.000 1-3 + aeration + degassing of CO 2 2 Euro Reuse intensive 10.000 1,5-5 Pure oxygen + mechanical filtration 2-3 Euro Partly Recirculation Moderate Recirculation Intensive Recirculation 5.000 1,5-3 + biological filtration 3-4 Euro 400-700 2-8 50-400 2-8 + indoor +UV disinfection + temperature control +nitrate removal + phosphor removal +sludge thickening 8-10 Euro 10-12 Euro
Definition of Re-Circulation Water exchange per amount of feed put into the system per day is the most accurate definition. Water exchange per kg feed = Water exchange/day (m 3 /day) Feeding/day (kg/day) Water exchange per kg feed = 120 (m 3 /day)_ 300 (kg/day) Water exchange per kg feed = 400 l/kg feed The water consumption per kg fish produced is thus depending on the farmers skill: If feed conversion ratio (FCR) is 1, the water exchange per kg fish produced will be 400 If FCR = 0,9 consumption will be 360 litre per kg fish produced If FCR = 1,1 consumption will be 440 litre per kg fish produced
Water flow through a Re-circulation system General principle MODERATE RAS: Water consumption 400 700 litre new water/kg fish produced/year Complexity Removal of phosphor and brownish colour C Biological filtration (anaerobe de-nitrification) B Disinfection (UV, Ozone) A Biological filtration (Remove ammonia & organic material) A Mechanical filtration (Removal of particles) Oxygenation & degassing (adding of O 2, removal of CO 2, N 2 ) Aeration 25% 50% 75% 100% Re-circulation Flow through systems 40.000-50.000 Litre of new water/kg fish produced/year Semi RAS (A) 2.000-5.000 Litre of new water/kg fish produced/year Moderate RAS (B) 400-700 Litre of new water/kg fish produced/year Intensive RAS (C) 50 400 Litre of new water/kg fish produced/year 10
Best Available Technologies for Aquaculture in the Nordic Area TemaNord 2013:529 Free download (406p/14Mb) www.norden.org/en/publica tions/publikationer/2013-529 40 pp summary in English Summary also available at Amazon: Aquaculture in the Nordic countries and the BAT concept ($ 1.25). Printed book: 425 DKK (ISBN 978-92-893-2560-8) 11
Unzip the potential.. Recirculated Aquaculture! Farm fish everywhere with very little water and a very low environmental footprint 12